FIGS. 1A and 1B are schematic cross-sectional views of a normal human vein V. The vein V includes a valve formed of two leaflets L. FIG. 1A shows the valve in an open position in which the leaflets L separate to allow blood to flow towards the heart in the direction indicated by arrows A1. FIG. 1B shows the valve in a closed position in which the leaflets L come together to block the flow of blood away from the heart in the direction indicated by arrows A2. FIG. 1C shows a vein V′ having a diseased or otherwise damaged valve comprised of leaflets L′. As shown in FIG. 1C, the leaflets L′ are structurally incompetent and allow venous reflux, or the flow of venous blood away from the heart (arrows A2). Venous reflux can lead to varicose veins, pain, swollen limbs, leg heaviness and fatigue, and skin ulcers, amongst other symptoms.
Venous reflux can occur anywhere throughout the venous system, which includes superficial veins (veins closer to the skin) and deep veins. Because deep veins are harder to access, deep veins are also harder to treat surgically. Existing methods for treating damaged or diseased vein valves in deep veins include surgical repair of the diseased vein and/or valve, removal of the damaged vein, and/or vein bypass. However, all of the foregoing treatment options include relatively lengthy recovery times and expose the patient to the risks involved in any surgical procedure, such as infection and clotting. Experimental treatments such as implantable venous valves, external venous valve banding, and heat-induced vein shrinkage have been attempted but each treatment has significant shortcomings. In addition, compression stockings are sometimes used to ameliorate symptoms but do not address the underlying problem. Accordingly, there exists a need for improved devices, systems, and methods for treating damaged or diseased valves.